LeetCode 424 - Longest Repeating Character Replacement - Rewritten NeetCode solution

class Solution:
    def characterReplacement(self, s: str, k: int) -> int:
        chars_in_the_current_window = defaultdict(int)
        longest_substring = 0

        l = 0
        for r in range(len(s)):
            chars_in_the_current_window[s[r]] += 1

            while _chars_other_than_the_most_common(l, r, chars_in_the_current_window) > k:
                chars_in_the_current_window[s[l]] -= 1
                l += 1

            longest_substring = max(longest_substring, _the_window_size(l, r))
        return longest_substring

def _chars_other_than_the_most_common(l, r, chars_in_the_current_window):
    return _the_window_size(l, r) - _the_number_of_occurrences_of_the_most_common_character(chars_in_the_current_window)

def _the_window_size(l, r):
    return r - l + 1

def _the_number_of_occurrences_of_the_most_common_character(chars_in_the_current_window):
    return max(chars_in_the_current_window.values())